Method and apparatus for grinding molds



April 18, 1944. w. A. MONTGIOMERY METHOD AND APPARATUS FOR GRINDING MOLD S A 4 Shee'ts-Shet i Filed June 7, 1945 W T/VEJS April 18, 1944. ,A MONTGOMERY 2,346,861

METHOD AND APPARATUS FOR GRINDING" MOLDS I 4 Sheets-Sheet 2 Filed June '7, 1943 QMN ANN

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April-18, 1944. .w. A, MONTGOMERY 2,346,861 METHOD AND APPARATUS FOR GRINDING MOI. |D,S I

Filed June 7, 1943 4 Shets-Sheet 3 .HTTORNEY 4 Sheets-Sheet 4 d mp 5 April 1944- w. A. MONTGOMERY METHOD AND APPARATUS FOR GRINDING MOLDS Filed June '7, 194a WITNESS Patented Apr. 18, 1944 MOLD William A. Montgomery, Burlington, N. J assignor to United States Pipe and Foundry Company, a corporation of New Jersey Application June 7, 1943, Serial No. 490,102

8 Claims. ('Cl. 51- 18) The invention relates to a method and apparatus for grinding the surface of the bore of a tubular body, and is directed specifically to grinding the bore of a mold used in casting pipe or the like centrifugally.

Such molds are usually made from heavy steel forgings and are provided with a bore of generally cylindrical shape. When these molds are in use it is desirable to grind the bore from time to time in order to clean the surface, that is, to remove rust, scale, and other. foreign material adhering thereto. It has also been the practice to grind such molds periodically for the purpose of roughening the inner surface in order to provide the necessary traction for a mold coating and for the molten metal. In casting certain compositions which do not shrink sufficiently upon cooling to permit the pipe to be easily withdrawn from the mold, it is sometimes desirable to taper the bore of the mold in order that the casting may be readily withdrawn.

.With the apparatus heretofore available for generally similar purposes it has not been postion,- taken with the accompanying drawings wherein:

Figs. 1 and 1 are plan views of the opposite ends of the mold grinding machine designed for practicing the invention, with parts thereof cut away; 7

Figs. 2 and 2e are longitudinal, vertical sectional views through opposite ends of the machine, parts thereof being broken away and other parts being omitted for clarity;

Fig. 3 is an end elevational view of the machine taken substantially on the line33 of Fig. 1*;

Fig. 4 is a transverse sectional view taken substantially on the line 44 of Fig. 1;

Fig. 5, 6 and 7 are transverse sectional views taken substantially on the lines 55, 6-6, and

sible to remove a substantial amount of metal from the bore of such a mold, and it has also been very difficult with available grinding or cutting apparatus to remove the metal evenly andluniformly from the surface of the bore. Furthermore, such apparatus as would appear to be adaptable to the purpose has been found tolbe altogether inoperative for taper-grinding the mold bore, or it could not .beso controlled as to provide a uniform taper from end to end of the bore, or throughout such length as might be desired.

-It is therefore one of the principal objects of the present improvement to provide a method and apparatus for removing a substantial amount of metal from the surface of the bore of a centrifugal mold or other comparable tubular body. Another object of the improvement is the provision. of a method and apparatus whereby a definite, measurable thickness may be removed from the surface of the bore of a centrifugal mold or other heavy tubular body by a grinding operation. A further object of the improvement is the provision of a method and apparatus forlength or throughout any desired portion thereof.

pther objects and advantages of the improvement will be apparent fromthe following descripl'-'l, respectively, of Fig. 1;

Fig. 8 is a transverse sectional view taken on the line 8-8 of Fig. 9;

Fig. 9 is a longitudinal sectional view showing the manner in which the grinder shaft ismounted in its tubular support;

Fig. 10 is a vertical sectional view through the needle valve utilized. for varying the linear speed of the grinding wheel in its translating movements; and

Fig. 11 is a horizontal sectional view through supported in a horizontal position by roller units a spaced from each other lengthwise of the mold and adjustable if desired in order to accommodate molds of different length. Each unit includes two laterally spaced rollers l2, each of which'is secured on an axle l3-the opposite ends of-which are mounted in suitable bearings M on g the upper edges of cross beams l5. The ends of cross beams 15 rest upon main longitudinal girders l6 which preferably extend throughout the length of the grinding apparatus together by tie beams ll.

One end of each axle 13 extends beyond the adjacent bearing l4 and has a grooved pulley; 58 secured thereon. Belts l9 passingyaround the grooved pulleys l8 of each roller unit'and around and are secured a grooved pulley 2D fixed on a shaft 2| beneath the roller units serve to drive the rollers I2 and thus rotate the mold It] in a given direction. The shaft 2| is supported in suitable bearings 22 secured to the lower edge of cross beams l5. The outer end of shaft 2| is connected with a gear box 23 containing suitable transmission mechanism driven by an electric motor '24.

The grinding device proper consists of a rotary grinding wheel 25 supported in such a manner that it may be moved back and forth throughout the length of the bore of the mold With the operating mechanism thus described, it will be apparent that movement of the piston 48 in one direction in the cylinder 49 will operate to move the carriage 29 in the same direction, and as a consequence the grinding wheel 25 will be translated at a uniform speed from one end to the other of the bore of the mold l0. It will also be apparent that,'w,hen the direction of flow of the motor fluid to the cylinder 49 is reversed by the operation of the four-way valve the piston 48 will be moved in the op- Hi and simultaneously rotated in a direction opposite to the direction of rotation of the mold. The grinder is secured on the outer end of a long shaft 26 which is mounted in suitable spaced bearings 21 within a tubular support 28." The end of the tubular support 28 opposite the grinding wheel 25is secured to a carriage 29 which is designed to be moved back and forth toward and away from the end of the mold ll] in order that the grinding wheel may be reciprocated throughout the length of the bore of the mold and completely hd awn t ereirom- I The carriage 29 is supported by wheels 33 which run on tracks 3| on the upper edges of the girders IS. A pair of pedestals 32 secured along the opposite edges of the carriage 29 serve as a. support for the grinder shaft 26 and the mechanism for rotating the same. Each pedestal 32 forms a bearing for he lower d of; a s ft 3 which extends .upwandly between two spaced Cross b ams 34 ovided w h s it b e tie la 35 for securing them together. Shafts 33 are threaded in sleeves 35 secured between the cross beams 34. and may be rotated by means of handles 3! in order to raise and lower the cross beams 34 and thereby adjust the grinding wheel 25 vertically to accord with the size and position of the mold -ill on the supporting and driving rollers |2.

The end of the tubular support 28 adjacent the carriage 29 is secured in a bracket 38 fixed to the lower edge of one of the cross beams 34.. The adjacent end of the grinder shaft 26 is provided.

with a grooved pulley 39 which is driven, by belts 40 passing arQ lnd a grooved pulley 4| on the shaft of a motor 42. The motor 42 is sup.- ported on a platform 43 carried by bracket arms 44 secured to one of the cross beams 34. As will beapparent from this construction, motor 42 drives the shaft 26, and thus provides the grinder 25 with rotary motion in a direction opposite to that of mold H).

The carriage 25 is moved toward and away handle 52 so as to direct the fluid to one end of the cylinder 49 through a pipe 53, or to the other end of the cylinder through a pipe 54. When the piston 48 is moving in one direction under the action of the motor fluid on one side thereof, the spent fluid on the opposite side of the piston is discharged through one or the other of the pipes 53, 54, thence through an exhaust pipe 55, connected to the four-way valve 5|.

posite direction, and consequently the grinding wheel 25 will be translated in the same direction.

at a uniform speed throughout the length of the bore of the mold to thus complete its reciproeating movement. Inasmuch as the grinding wheel 25 is adjusted in a vertical direction by means .of the handles 31 so that it rides upon the bottom of the bore of the mold I0, it will be maintained in gravitational contact with the surface of the bore throughout its reciprocatingthe mold it, means have been provided for uni-.

formly varying the exhaust of the spent fluid, and thus uniformly increasing or decreasing the linear speed of the grinder 25, as the piston 48 is moved in one direction or the other. This ex-i haust control means comprises a needle valve 58- arranged in the exhaust pipe 55 and provided. with actuating mechanism so designed that the:

valve is in the open position when the grinding wheel 25 is operating in what is to be the small.

end of the bore, and is in closed position when the grinding wheel 25 is operating in the other end of the bore. The mechanism for operating the needle valve 56 comprises a grooved pulley 51 secured on the valve stem 58 and carrying a belt 59 which passes around a grooved pulley secured on stub shaft 6| having a bearing support on bracket arm 62. A gear 63 secured on stub shaft 6| meshes with a pinion B4 fixed on the upper end of a shaft 65 the lower end of which is mounted in a bearing 66 on one ofthe tie beams grooved pulley 5! secured thereon, and this in turn is. driven by an endless. cable 58 passing.

therearound and extending beneath the. carriage 29 and over a sheave 69 suitably supported on a}.

.tie beam i! at the outer end of the machine.

As the cable 68 is suitably secured to. the car-'- riage 2.9 at some point, such as indicated at- 10, it will be apparent that movement of theis moved; from open to closed position and vice.-

versa. during the movement of the grinder 25 from one end of the bore of the mold |0to the other. As a consequence of this variable control of the exhaust fluid, the reciprocating movement of the rindin wheel will be so controlled that.

it moves inwardly within the bore at a uniformly decreasing speed a d at a unifo ly c e sin speed in the opposite direction. As, a result of.

this variation in the reciprocating movement. of

The shaft 65 is rotated by athe grinding wheel 25 while rotating uniformly in a direction opposite to the direction of rotation of themold It, the eifectiveness of the grinding action increases uniformly as the grinding wheel moves toward the bell end of the mold and decreases uniformly as it moves away from the bell end. The bore of the mold will therefore be taper-ground uniformly from end to end. In order that the grinding wheel 25 and the outer end of the tubular support 28 may be supported when the grinder 25 is withdrawn from the mold Ill, a suitable rest is provided in the form.

of a grooved wheel 12 mounted on the upper end of a post 13 the'lower end of which is adjustable in an upright sleeve M on a small carriage. 15. The post 13 may be held in various positions of adjustment by a hand operated set screw 16. The carriage I is supported by wheels 11 which run upon the tracks 3! heretofore described.

A pipe 18 secured on the tubular support 28 by suitable brackets 19 has its outlet end 80 positionedadjacent the grinding wheel in order that compressed air may be supplied therethrough for the purpose of clearing away dust and other small particles of material produced during the-grinding operation. The bell end of the mold I8 is also provided with exhaust means for discharging the dust and particles of metal. This exhaust means comprises an exhaust head in the form of a casing 8| having its inlet connected to the bell end of the mold H] by a tele- Scoping sleeve 82 and having its outlet 83 connected to an exhaust fan operating in the casing 84 and discharging through outlet pipe 85.

While any other suitable means may be utilized for placing the mold It on the supporting and driving rollers l2 and removing it therefrom, a skid device such as shown in Figs. 1 and 4 may be employed. This device comprises a pair of skid rails 86 each of which has one end pivotally supported on a pillow block 81, resting on one of the girders Hi. The opposite end of each skid rail 86 extends outwardly beyond the adjacent girder I6 and is secured to a side rail 88. The side rail 88 is supported on the upper end of a piston rod 89 which is connected to a fluid-oper-v ated piston in a cylinder 90 the lower end of which is pivoted upon a suitable base 9i.

With a skid device of this kind, the mold to be ground may be transported on a railroad car or other suitable conveyor into a position alongside the grinding apparatus and rolled onto the skid rails 88 when the latter are in a horizontal position. When the pressure fluid is exhausted from beneath the piston in cylinder 90, the free edge of the skid device will move downwardly so as to lower the mold into position on rollers I2. By a reverse of this operation, the mold may be lifted free of rollers I2 and removed from the grinding machine.

The operation of the machine has been sufliciently described in connection with the structural details referred to above, and the novel grinding method will also be clear from the above description. While the invention has been described with particular reference to the grinding of a centrifugal mold used in casting pipe, it will be understood that it is also useful for various other grinding operations. The above described means for controlling the exhaust of the spent motor fluid has been found to be a simple and accurate way for uniformly varying the speed of the grinder in its translating movements, and in adapting the other features of the machine to the taper-grinding of a cylindrical bore, or in cleaning a previously formed taperedbore; As will be apparent, however, from the above description and from the apparatus shown in .the drawings, the machine may be readily adapted for grinding or cleaning a cylindrical bore by omittingthe needle valve 56 from the exhaust pipe'for the spent fluid, or by replacing the tapered valvemember H with a valve member of uniform diameter. Various other changes may be made in the form, arrangement and operation of the apparatus and i'nthe parts thereof, and such changes arecontemplated without departing from the invention as defined by the appended claims, I

WhatIdesire to claim is: I H l. The method of tapering the bore of a cylindrical metal mold, which comprises supporting the mold horizontally and rotating the same in one'direction aboutits longitudinal axis, reciprocating a grinding wheel from end to end of the bore and in gravitational contact with the surface thereof whilev rotating it in a direction opposite to the direction of rotation of the mold, uniformly accelerating the reciprocating movement of said grinding wheel in one direction, and uniformly retarding its reciprocating movement in the opposite direction.

2. Apparatus for taper-grinding the inner surface of a tubular metal body, comprising means for supporting the tubular body horizontally, means for rotating the tubular body about its longitudinal axis, a rotary grinder supported-for reciprocating movementin the bore of the tubular body and in'gravitational contact therewith, means for rotating said grinder, means for :reciprocating said grinder, and control mechanism for uniformlyincreasing the rate of recipro'oat-" ing. movement of said grinder in one direction and uniformly decreasing its rate of reciprocating movement in the reverse direction.

3.. In apparatus for grinding the surface of a cylindrical metalmold, means for supporting the mold horizontally and rotating thesame inone direction about its longitudinal axis, a carriage I movable toward and away from one end of the mold in the direction of the axis of the mold, arotatable shaft. having one end supported by said carriage and a rotary grinder mounted on its opposite end for reciprocating movement 1ongitudinally of the mold and in contact therewith upon movement of said carriage toward and away from the mold, means on said carriage for rotating said shaft in a direction opposite to the direction of rotation of the mold, means for moving said carriage to reciprocate said grinder longitudinally of the mold, and speed regulating means for accelerating the movement of said carriage in one direction and retarding its movement in the opposite direction.

4. In apparatus for grinding the inner surface of a cylindrical metal mold, means for supporting the mold horizontally and rotating the same in one direction about its longitudinal axis, a carriage movable toward and away from one end of the mold in the direction of the axis of the mold, a rotatable shaft having one end supported by said carriage and a rotary grinder mounted on its opposite end for reciprocating movement longitudinally within the bore of the mold and in contact therewith upon movement of said carriage toward and away from the mold, means on said carriage for rotating said shaft in a direction opposite to the direction of rotation of the mold, means for moving said carriage to reciprocate said grinder within the bore of the mold, and

speed regulating means for uniformly accelerat-.

ing the movement of said carriage in one direction and uniformly retarding its movement in the opposite direction.

5. In apparatus for grinding the inner surface of a cylindrical metal mold, means for supporting the mold horizontally and rotating the same in one direction about its longitudinal axis, a carriage movable toward and away from one end of the mold in the direction of the axis of the mold, a rotatable shaft having one end supported by said carriage and a rotary grinder mounted on its opposite end for reciprocating movement 1ongitudinally within the bore of the'mold and in contact therewith upon movement of said carriage toward and away from the, mold, means on said carriage for rotating said shaft in a direction opposite to the direction of rotation of the mold, means for moving said carriage to reciprocate said grinder within the bore of the mold, and speed regulating means responsive to the movement of said carriage for varying the linear speed of said grinder in accordance with its position longitudinally of the mold.

6. In apparatus for grinding the inner surface of a cylindrical metal mold, means for supporting the mold horizontally and rotating the same in one direction about its longitudinal axis, a carriage movable toward and away from, one end of the mold in the direction of the axis 'of the mold, a rotatable shaft having one end supported by said carriage and a rotary grinder mounted on its opposite end for reciprocating movement longitudinally within the bore of the mold and in contact therewith upon movement of said carriage toward and away from the mold, means on said carriage for rotating said shaft in a direction opposite to the direction of rotation of the mold, means for moving said carriage to reciprocate said grinder within the bore of the mold, fluid pressure means for resisting the movement of said carriage in both directions, and regulating means for varying the effectiveness of said fluid pressure means in accordance with the position of said carriage in its longitudinal movements.

'7. In apparatus for grinding the inner surface of a cylindrical metal mold, means for supporting the mold horizontally and rotating the same in one direction about its longitudinal axis, a carriage movable toward and away from one end of the mold in the direction of the axis of the mold, a rotatable shaft having one end supported by said carriage and a rotary grinder mounted on its opposite end for reciprocating movement longitudinally within the bore of the mold and in contact therewith upon movement of said carriage toward and away from the mold, means on said carriage for rotating said shaft in a direc-. tion opposite to the direction of rotationof the mold, fluid pressure motor means for moving said carriage to reciprocate said grinder within the bore of the mold, fluid pressure retarding means for resisting the movements of said carriage, and means responsive to the movement of said car-. riage for varying the resistance of said retarding means and thereby varying the speed of said car-r riage in accordance with its position.

8. In apparatus for grinding the inner surface of a cylindrical metal mold, means for supporting the mold horizontally and rotating the same in, one direction about its longitudinal axis, a carriage movable toward and away from one end of the mold in the direction of the axis of the mold, a rotatable shaft having one end supported by.

said carriage and a rotary grinder mounted on its opposite end for reciprocating movement longitudinally within the bore of the mold and in contact therewith upon movement of said carriage toward and away from the mold, means on said carriage for rotating said shaft in a direction opposite to the direction of rotation of the mold,

, a cylinder supported longitudinally of the mold and having therein a fluid-actuated piston conexhaust means, and means for actuating said:

valve in response to the movement of said carriage to uniformly accelerate the discharge of spent fluid as said carriage moves in one direction.

and uniformly retard the discharge of spent fluid as said carriage moves in the opposite direction.

\WILLIAMA. MONTGOMERY. 

